Configurable imaging system

ABSTRACT

A method for use in an imaging system having an image source and a plurality of microtile units for generating respective portions of the image is provided, each microtile unit including a self-contained screen and a rear projector for projecting the image on the screen, the method for at least one of self-aligning, colour matching and brightness matching the image portions across successive adjacent microtile units. The screen is over-scanned so that a portion of an edge of each image spills over onto a side wall of the microtile unit adjacent a further one of microtile units. Light from the image is permitted to spill through the side wall into the further microtile unit. The light is detected within the further microtile unit. The image is adjusted in response to detection of the light within the further microtile unit so as to at least one of align, color match and brightness match the image between the plurality of microtile units.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 11/748,255, filed May 14, 2007, and entitled “Configurable Imaging System”, which is hereby incorporated by reference.

FIELD

The following is directed in general to imaging systems, and more particularly to an imaging system having a plurality of microtile units for generating respective portions of a composite image in which light detection us used for at least one of self-aligning, color matching and brightness matching.

BACKGROUND

A large number of applications and potential applications exist for imaging systems such as projection displays that are used to display information. Such applications include, but are not limited to, general indoor signage (e.g. shopping malls, arcades, etc.), transportation signage (e.g. arrival/departure times, etc.), in-lobby signage for office buildings, control rooms, restaurants signage, etc.

The currently prevailing paradigm in the projection display industry is that improvement must be based on higher light power (lumens) at higher resolutions and progressively lower cost. This paradigm is based on the concept that higher resolution and higher power are necessary to develop larger displays with acceptable image quality and brightness using a least number of projectors. This paradigm has served the industry well, but has a number of drawbacks which include: the significant cost associated with higher resolutions, limitations in projector resolution due to light valve/panel design, increased weight, increased cost and increased noise levels associated with cooling systems necessary to accommodate high power illumination.

Moreover, the currently prevailing paradigm is based on static size and configuration of displays. Thus, whereas it is known to provide large displays by assembling a multiplicity of small displays in an array (see, for example, WO 2006/115852 (Ostendo)), there is no provision for creating customized shapes and dimensions of display from such multiple small displays.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the preferred embodiment is set forth in detail below, with reference to the following drawings, in which:

FIG. 1 is a block diagram of an exemplary imaging system comprising a plurality of microtile units, according one embodiment of the invention;

FIG. 2 depicts front and rear perspective views of a pair of block microtile units;

FIGS. 3A and 3B depict exemplary configurations of microtile units to create a composite image;

FIG. 4 depicts grid microtile units according to a second embodiment of the invention, wherein FIG. 4A shows front and rear views of a grid microtile unit, FIG. 4B shows an array of grid microtile units for displaying a composite image on the rear of a display screen, and FIG. 4C is a front view of the array and screen of FIG. 4B

FIG. 5 shows an alternative embodiment of grid microtile unit;

FIGS. 6A and 6B are front and perspective views, respectively, showing a feature of the block microtile unit for effecting self-alignment of images across successive adjacent microtile units;

FIG. 7 is a block diagram showing an arrangement of microtile units, input modules and a system controller according to an exemplary embodiment; and

FIG. 8 is a block diagram showing internal circuitry of a video routing and processing module for an exemplary microtile unit according to the invention.

DETAILED DESCRIPTION

An aspect of the specification provides a method for use in an imaging system having an image source and a plurality of microtile units for generating respective portions of the image, each microtile unit including a self-contained screen and a rear projector for projecting the image on the screen, the method for at least one of self-aligning, colour matching and brightness matching the image portions across successive adjacent microtile units. The method comprises: over-scanning the screen so that a portion of an edge of each image spills over onto a side wall of the microtile unit adjacent a further one of microtile units; permitting light from the image to spill through the side wall into the further microtile unit; detecting the light within the further microtile unit; and adjusting the image in response to detection of the light within the further microtile unit so as to at least one of align, color match and brightness match the image between the plurality of microtile units.

Another aspect of the specification provides, in an imaging system having an image source and a plurality of microtile units for generating respective portions of the image and being arranged in any one of a plurality of geometrical configurations, a method of detecting the one of the geometrical configurations. The method comprises: for each respective one of the microtile units detecting the presence of any other microtile unit to one side of the one of the microtile units and detecting the presence of any other microtile unit to another side of the one of the microtile adjacent the one side; and creating a map of the one of the geometrical configurations based on detection of the presence.

Detecting can include causing each the respective one of the microtile units to generate a signal at the one side and a signal at the another side for detection by the any other microtile unit. The signal can be generated by an LED and can be detected by a photodetector.

A further aspect of the specification provides an imaging system, comprising: an image source; and a plurality of microtile units for generating respective portions of the image, each microtile unit including a self-contained screen, at least one surface having an aperture therein and an opposite surface having a photodetector therein, and a rear projector for projecting the image on the screen and over-scanning the screen so that a portion of an edge of each image spills through the aperture onto the photodetector of a further one of microtile units adjacent the microtile unit so as to be detected within the further microtile unit, and control circuitry for adjusting the image in response to detection of the light within the further microtile unit so as to at least one of align, color match and brightness match the image between the plurality of microtile units.

In FIG. 1, an exemplary imaging system is shown comprising a plurality of series connected microtile units or projection heads 1 assembled to form an array. Cables 5 are used to connect the microtile units 1 in any sequence. According to one embodiment standard CAT 5 cabling is used having four twisted wire pairs for data and command message transmission, wherein command messages are embedded in the blanking interval of a video data stream. Data transmission preferably occurs at a rate of about 5 Gpbs.

Each microtile unit 1 contains a light engine and circuitry (including, for example, a microprocessor, RAM frame buffer and video processing to provide image capture, resizing, color matching, edge blending, etc.), discussed in greater detail below with reference to FIGS. 7 and 8. Data received from an adjacent microtile unit 1 via cable 5 is buffered and retransmitted to the next series-connected microtile unit 1 (or system control unit 7 or input module 9). The video processing circuitry preferably includes modules for sub-image capture and resizing, color matching, edge blending, uniformity correction and 2D keystoning. Also, as discussed in greater detail below with reference to FIGS. 6A and 6B, color, brightness and image uniformity may be achieved using intelligent self-alignment of images between microtile units 1 and intelligent brightness and color control.

At least one system control and power unit 7 is connected to an available port on one of the microtile units 1 for providing power (e.g. 48 V DC) and to facilitate automatic detection of the configuration of interconnected microtile units 1, as described in greater detail below. Typically, the system control and power unit 7 includes at least one Ethernet, USB and/or infrared port to a user interface (not shown), and generates full frame static images (i.e. transfer image content from a SD (Secure Digital) flash card to a frame buffer for display), as well as implementing OSD (on-screen display) overlays (OSD allows the user to view and change display settings on-screen).

At least one input unit 9 is also connected to an available port on one of the microtile units 1 for providing a video and/or image source for display by the microtile units 1. Preferably, the input unit 9 performs video processing, such as de-interlacing, scaling, frame rate conversion, etc.

Each microtile unit 1 requires electronic communication only with adjacent microtile units (or input unit(s) 9 or the system control unit 7, any of which can be connected anywhere in the chain of series-connected microtile units 1), provided that an electronic signal path from the system control and power unit 7 and input units 9 extends via respective microtile units 1 and associated cables 5 to each microtile unit 1.

As discussed in greater detail below, with reference to FIGS. 2 and 3, a variety of different mechanical coupling mechanisms are possible for achieving accurate alignment of each microtile unit 1 with respect to its adjacent interconnected microtile units 1.

According to one embodiment, the microtile units are in the form of “block” microtile units 21, as shown in FIG. 2. Coupling mechanisms 23 permit registration or alignment of a microtile unit 21 with other microtile units based on the shapes of protrusions on respective side surfaces of each microtile unit. The front surface of each microtile unit 21 comprises a self-contained screen 24. A small rear projector (including light source, light valve, optics and associated electronics) is provided within each microtile unit 21 for projecting an image on screen 24. According to an exemplary embodiment, the light source is implemented using LEDs, although it is contemplated that lasers or other light sources may be utilized, the selection and implementation of which would be known to a person of ordinary skill in the art.

A pair of LEDs 26 and Photodetectors 28 is provided on each of the top, bottom, left and right surfaces, to permit of self-organizing and configuring of the microtile units 1, as discussed in greater detail below.

Also discussed in greater detail below, each microtile unit 21 projects a portion of a composite image (preferably at SVGA resolution to enable small pixel pitch (under 1 mm)), as shown in FIGS. 3A and 3B. It will be noted that microtile units 21 are not required to be arranged in rectangular configurations, thereby resulting in significant flexibility in terms of display design (FIG. 3A).

According to a successful prototype, each block microtile 21 has a diagonal dimension of approximately 400 mm for projecting an image having a 4:3 aspect ratio, although other dimensions and aspect ratios are contemplated. However, a person skilled in the art will appreciate that a range of display sizes and shapes may be accommodated. For an indoor display, such as shown in FIG. 3A, it is contemplated that 500 nits of brightness will be sufficient, although other brightness may be provided depending on the illumination source, optical design and screen size.

Turning to FIG. 4A, an embodiment of a “grid” microtile unit 41 is set forth capable of connection with other grid microtile units as shown in FIGS. 4B and 4C. The grid microtile units 41 are similar in functionality to the block microtile units 21 of FIG. 2. However, there is no self-contained screen in the grid microtile unit 41. Tubular coupling mechanisms 43 permit interconnection between adjacent microtile units 41 via complementary threaded male portions 44 and female coupling sleeves 46. A small rear projector 47 (including light source, light valve, optics and associated electronics) is provided within each microtile unit 41 for projecting an image onto a remote screen (such as screen 49 depicted in FIGS. 4B and 4C). As discussed above, each microtile unit 41 projects a portion of a composite image onto the remote screen 49. FIGS. 4B and 4C show an array of interconnected grid microtiles 41 projecting an image onto screen 49 (wherein FIG. 4B is a view showing projection onto the rear surface of the screen whereas FIG. 4C shows the image as displayed on the front surface of the screen).

FIG. 5 shows yet a further alternative embodiment of microtile unit 42 which is in the shape of a block incorporating a light engine and circuitry and a front surface comprising a self-contained screen 24 like the block microtile units 21, but which includes tubular coupling mechanisms 43, as in the grid microtile embodiment of FIG. 4. Numerous other configurations may also be adopted.

As discussed briefly above, self-alignment of images across successive adjacent microtile units may be accomplished by electronic adjustment of the image upwardly, downwardly, right, left, via roll, pitch and yaw. This dramatically reduces or eliminates the need for expensive mechanical adjustments and provides for simple correction of zoom errors.

One such alignment process (for use with block microtile units 21) requires slightly over-scanning the screen 24 so that a small portion of the edge of each image (e.g. line 60) spills over onto a side wall of the microtile unit, as shown in FIGS. 6A and 6B, such that light spills (e.g. at 61) through a pinhole 62 therein, and is detected by a sensor 63 disposed in a small opening 65 in the adjacent screen. By controlling the image content in the overspill area, the sensor 63 detects when the image is aligned properly. Using several of these pinhole/sensor pairs, keystoning can be sensed and adjusted for. By sensing the color intensity of the light spilling through the pinhole 62, the system can automatically adjust for consistent intensity and colour. Alternatively, it is contemplated that the sensors may be placed in the same cabinet as the projection system and only self-align within the block itself.

Another alignment process (for use with grid microtile units), requires overlapping the image portions projected by successive microtile units onto the screen 49, and using known edge blend techniques to eliminate perceived borders between the image portions. Examples of such edge blend techniques are described in U.S. Pat. No. 4,974,073 entitled “Seamless Video Display”; U.S. Pat. No. 5,136,390 entitled “Adjustable Multiple Image Display Smoothing Method and Apparatus”; U.S. Pat. No. 6,115,022 entitled “Method and Apparatus for Adjusting Multiple Projected Raster Images and U.S. Pat. No. 6,760,075 entitled “Method and Apparatus for Seamless Integration of Multiple Video Projectors”.

Image uniformity may be achieved through careful optical design and through electronic image adjustment, as well as through screen design (with careful consideration to viewing angles, contrast and related issues). Careful consideration of these factors is important to achieving a pleasing multi-tiled display while avoiding ‘hot-spots’, minimizing reflections from ambient light and unpleasant screen-to screen-variation. ‘Optical’ screen designs may be used to achieve this (i.e. a single element or multiple element rear-projection screen that is designed to achieve a predefined optical function, for example: to control the light path as to enhance the quality of the display images for optimum viewing conditions).

According to an important aspect of the invention, the array of microtile units 1 self-organizes based on the number and configuration of the microtile units. One exemplary method of self-organizing and configuring is implemented under control of the system control unit 7, although it is contemplated that self-organizing and configuring may also be performed as a distributed process among the interconnected microtile units 1.

The exemplary method of self-organizing and configuring of microtile units 1 comprises three phases: Address Assignment; Module Identification; and Array Mapping. Once these three phases are complete, the system controller unit 7 contains a complete map of the interconnected microtile units 1 for the purpose of distributing control signals and image content over the entire array in accordance with the detected shape and size of the array. The system control unit 7 initiates the self organization process as part of the power-up procedure. Preferably, the input modules 9 and microtiles units 1 support hot plugging, so that a user interface option may be provided to rerun the self organization process on an as-required basis.

In the Address Assignment step, the system control unit 7 issues an “AUTOADDRESS 1” command to the first ‘leftward’ module 1 to which it is connected in the series-connected ‘chain’ of units (i.e. the unit 1A in FIG. 1). The receiving unit 1A responds by setting its internal address to “1”, and sends an “AUTOADDRESS 2” command to the next module (unit 1B) in the daisy chain connection (i.e. via the cable 5 connected to its output port). Unit 1B, upon receiving the “AUTOADDRESS 2” command sets its internal address to “2”, and sends an “AUTOADDRESS 3” to unit 1C. Unit 1C in turn configures the next microtile unit in the chain, and so on. In this manner, all microtile units 1 (and any input modules 9 to the left of the system control unit 7) are assigned unique ID numbers.

During the Module Identification phase, the system control unit 7 determines what modules it is connected to by requesting the modules at addresses 1, 2, 3, etc., to identify themselves. As discussed above in the Address Assignment phase, each microtile unit 1A, 1B, etc. (and any connected input module 9) is programmed to return a unique identifying code. This allows the system control unit 7 to know what is connected at address 1, address 2, address 3, etc. When a request is met with no response, the system control unit 7 will know it has reached the end of the chain.

Once all items connected to the left of the system control unit 7 have been assigned an address and have been identified, the entire self-organization process is repeated for any units (microtile units 1 and/or input modules 9) to the right of the system control unit, where the first unit to the right (i.e. unit 1F in FIG. 1) is allocated the next sequential address.

The Array Mapping phase is used to establish the spatial relationship between all of the connected microtile units 1. As briefly discussed in connection with FIG. 2, an LED 26 and photodetector 28 pair is provided along each surface of a microtile unit 1. According to one embodiment of the Array Mapping phase, the LEDs 26 on the top and left side of each individual microtile unit 1, and photodetectors 28 along the bottom and right side of each microtile unit, are paired such that the photodetectors are sensitive to the wavelengths emitted by the LEDs. The placement of LEDs 26 and photodetectors 28 is such that the top and left LEDs of one microtile unit are aligned with photodetectors on adjacent microtile units to the top and left, respectively, such that only one photodetector 28 is capable of ‘seeing’ any given LED 26 within the array.

The LED 26 and photodetector 28 pairs may also be used for optically communicating video and control signals between respective modules 1, 7 and 9, as an alternative to serial data cables 5.

The Array Mapping phase starts with the system control unit 7 sending a command to microtile unit 1A to turn on its top surface LED 26. The system control unit 7 then queries all other microtile units 1 see which one is capable of detecting the illuminated LED (i.e. via an associated photodetector 28). Because of the alignment of LEDs and photodetectors discussed above, only one microtile unit 1 (or none) will respond in the affirmative. The system control unit 7 then knows which microtile unit (i.e. unit 1B) is directly above unit 1A. The system control unit 7 then commands microtile unit 1A to turn off its top LED 26 and illuminate its left-surface LED 26. Another query is sent by system control unit 7 to the array of microtile units in order to reveal the address of the unit immediately to the left of microtile unit 1A. If no microtile unit responds in the affirmative, then the system control unit 7 knows that there is no unit adjacent and to the left of unit 1A, and therefore a gap or a boundary has been located in the array. System control unit 7 then proceeds to repeat the process for unit 1B. By carrying out this procedure through the entire array, system control unit 7 builds a map indicating precisely how the array is physically configured. This information is then used by the system control unit 7 to determine the portion of the image each individual microtile unit is to be responsible for, and to relay that information to each microtile unit 1.

A person skilled in the art will appreciate that the Array Mapping phase does not need to be done with LEDs and photodetectors. For example, a set of electrical contacts could also be used (especially for the grid microtile embodiment of FIG. 4), or other similar physical detection may be used to establish which units are physically adjacent to each other.

Turning to FIG. 7, a block diagram is provided showing electronic components of an arrangement of microtile units 1, input modules 9 and a system controller 7 according to an exemplary embodiment. Each microtile unit 1, input module 9 and a system controller 7 incorporates a video routing and processing module comprising PLD/ASIC 71 and frame buffer 73, the details of which are set forth in FIG. 8, for receiving, transmitting and operating on video and command signals. The functional circuitry of each video routing and processing module is identical but operates on video and command signals in accordance with its ‘personality’ as a microtile unit 1, input module 9, or system controller 7. Thus, the video routing and processing module of each microtile unit 1 communicates with an associated mosaic display module comprising digital to analog converter (DAC) 75 and DVI transmitter 77 for transmitting video signals to an associated light engine via a DVI connector 79. Likewise, each input module 9 includes a DVI receiver 81 for receiving video signals from a source, such as a PC via a DVI connector 79, and each system controller 7 includes a CPU 83 for exchanging command/control messages with other units, via its video routing and processing module.

Video signals are input to the video routing and processing module via an input bus 85, and video signals are output therefrom via an output bus 87. CPU command signals are exchanged via a control bus 89.

Turning to FIG. 8, details of an exemplary video routing and processing module are set forth. Test patterns block 101 is used to generate test images for testing interconnection of modules and as an aid in set up for image geometry correction, etc.

Crosspoint switch 103 functions as a multiplexer under control of control logic 105. Control logic 105 controls operation of the video routing and processing module in one of either a “master mode” or “slave mode”, as discussed in greater detail below.

The auto setup block 107 receives input video signals from DVI receiver 81 via input bus 85, performs autodetection of the video format (e.g. VGA, XGA, etc.) and optimizes the video signal for display at an adjacent microtile unit 1. The video signal is loaded into a FIFO 109 for synchronizing the timing of the input video source to the internal processor clock (CLK), and output therefrom to the crosspoint switch 103. As an alternative, the functionality of auto setup block 107 may be incorporated directly into the DVI input module.

A PCS (Physical Coding Sublayer) block 111 provides an interface between the signals on cable's 5, the Crosspoint switch 103 and control logic 105. The PCS block 111 includes a pair of CDR (clock data recovery) decoder circuits and a pair of serialize encoder circuits for each serial cable 5. A PLL 113 (phase locked loop) is connected to each decode and encode circuit to provide proper synchronization of the multiple serial data streams. The lower CDR decoder circuit (Ser1Rx2 and Ser2Rx2) is, in turn, connected to a command extract block, while the lower serialize encoder circuits receives signals from a command insert block. Packetized data received from cable 5 is unpacked via an unpack data block before application to crosspoint switch 103. Conversely, signals received from crosspoint switch 103 are packetized in packetize data blocks for transmission via cable 5.

When operating in a “master mode”, in which the video routing and processing module forms part of the control module 7, command data is extracted from the video blanking interval of video signals carried by cable 5 and inserted into the data stream (e.g. using 8B10B encoding) via the command extract and insert blocks, respectively, under control of CPU 83. When operating in a “slave mode”, wherein the video routing and processing module forms part of microtile unit 1 or input module 9, command data embedded in the video stream (e.g. the AUTOADDRESS commands used for self-organizing and configuring of microtile units 1) are extracted and applied to control logic 105. More particularly, the packetize and unpack data blocks perform the necessary conversion between 8B10B encoded data blocks and raster scan video data signaling.

CPU interface 115 exchanges commands between control logic 105 and the CPU 83 (where the video routing and processing module forms part of the control module 7). Register file 117 stores configurations and settings for control logic 105.

An OSD (On Screen Display) module 119 for overlaying user menus generated by the CPU 83 on video data transmitted to the various microtile units 1.

A 3×3 FIR filter 121 is provided for anti-aliasing the input video signal to permit keystone correction, as is known in the art. A further FIR filter 123 performs bilinear image scaling (2×2 scalar filter), and rotation (keystone correction) based on information received from the alignment process discussed above in connection with FIGS. 6A and 6B. Frame buffer 73 stores portions of the required image and downloads the necessary filter coefficients to the filter 123. After scaling, the filter 123 performs an additional high pass filter operation on the output video signal for increased image sharpness (3×3 sharpness filter).

Filtered signals output from filter 123 are applied to a block 125 via line buffer 124, for color matching, edge blending, uniformity correction and gamma correction. For color matching, block 125 implements a 3×3 (RGB) color correction matrix based on input from the sensors discussed above in connection with FIGS. 6A and 6B to correct color differences resulting from manufacturing tolerances associated with the microtile units 1, as well as the effects of temperature and aging on the illumination light source. Edge blending is used for the “grid” microtile embodiment of FIGS. 4A, 4B and 4C, as is known in the art. Likewise, gamma correction is performed in a conventional manner.

An output timing block 127 includes a further PLL to accommodate various display types and programmable output timing.

Preferably, the module also includes a GPIO (General Purpose Input/Output) block 129 for providing a set of 10 ports which can be configured for either input or output, and to support common bus protocols such as the I²C (Inter-Integrated Circuit), serial computer bus 133 described in U.S. Pat. No. 4,689,740.

An IR receiver 131 is provided for remote control of the associated module 1, 7 or 9.

A fan 135 provides cooling for the module (whether a microtile unit 1, system control unit 7 or input module 9), in a well-known manner.

Although not shown, GPIO 129, IR receiver 132, and I²C interface 133 are connected to control logic 105.

A person skilled in the art, having read this description of the preferred embodiment, may conceive of variations and alternative embodiments. For example, although the embodiment of FIG. 1 includes a single source of power 7, which is distributed amongst the plurality of microtile units 1, it is contemplated that each microtile unit 1 may incorporate its own power supply, especially for small configurations of microtile units 1. Likewise, it is contemplated that, where as the illumination for the microtile units 1 discussed above is self-contained, light from one or more light sources may be distributed to multiple microtile units 1.

All such variations and alternative embodiments are believed to be within the ambit of the claims appended hereto. 

1. For use in an imaging system having an image source and a plurality of microtile units for generating respective portions of said image, each microtile unit including a self-contained screen and a rear projector for projecting said image on said screen, a method of at least one of self-aligning, colour matching and brightness matching said image portions across successive adjacent microtile units, comprising: over-scanning said screen so that a portion of an edge of each image spills over onto a side wall of said the microtile unit adjacent a further one of microtile units; permitting light from said image to spill through said side wall into said further microtile unit; detecting said light within said further microtile unit; and adjusting said image in response to detection of said light within said further microtile unit so as to at least one of align, color match and brightness match said image between said plurality of microtile units.
 2. In an imaging system having an image source and a plurality of microtile units for generating respective portions of said image and being arranged in any one of a plurality of geometrical configurations, a method of detecting said one of said geometrical configurations, comprising: for each respective one of said microtile units detecting the presence of any other microtile unit to one side of said one of said microtile units and detecting the presence of any other microtile unit to another side of said one of said microtile adjacent said one side; and creating a map of said one of said geometrical configurations based on detection of said presence.
 3. The method of claim 2 wherein said detecting comprises causing each said respective one of said microtile units to generate a signal at said one side and a signal at said another side for detection by said any other microtile unit.
 4. The method of claim 3, wherein said signal is generated by an LED and detected by a photodetector.
 5. An imaging system, comprising: an image source; and a plurality of microtile units for generating respective portions of said image, each microtile unit including a self-contained screen, at least one surface having an aperture therein and an opposite surface having a photodetector therein, and a rear projector for projecting said image on said screen and over-scanning said screen so that a portion of an edge of each image spills through the aperture onto the photodetector of a further one of microtile units adjacent said microtile unit so as to be detected within said further microtile unit, and control circuitry for adjusting said image in response to detection of said light within said further microtile unit so as to at least one of align, color match and brightness match said image between said plurality of microtile units. 